1. Field of the Invention
The present invention relates to a fuel supply system for automobiles with a fuel tank to which are connected a filler pipe and at least one vent for venting the tank during operation of the automobile and one vent for venting the tank during refueling of the tank.
2. Description of the Related Art
An essential component of a fuel supply system is the fuel tank which contains the fuel needed for supplying the internal combustion engine. Connected to the fuel tank are a filler pipe for refueling and at least one vent for venting the tank during operation and a vent for venting the tank during refueling. Fuel tanks are available as containers of metal and of synthetic material.
The volume of fuel removed from the fuel tank during operation of the internal combustion engine must be replaced by air in order to avoid a pressure difference. This is effected through the operation vent. For this purpose, one or more operation vent lines, such as hoses or pipes, are provided on the fuel tank for connecting the fuel tank to the ambient air. This is usually effected by an activated carbon filter which is mounted in the vent line and neutralizes the gasoline vapors.
In addition to the operation vent, a refueling vent is provided on the fuel tank. This vent composed of one or more lines, such as hoses or pipes, has the purpose of conducting out of the fuel tank the gas volume displaced by the inflowing fuel during refueling. As a rule, the displaced gases are neutralized in an activated carbon filter and are then discharged into ambient air.
In fuel supply systems of the conventional type, the individual operation vent lines and refueling vent lines are located individually outside of the fuel tank. Consequently, a separate connection to the fuel tank with an opening in the wall of the fuel tank is required for each line. Another connection opening is required for the filler pipe. This is cumbersome with respect to manufacturing technology. Moreover, high requirements must be made of the tightness of the connections in order to ensure the operational safety of the fuel supply system.
In addition, the connecting and sealing locations are potential weak points for an escape of fuel gases by permeation, i.e., when fuel gases permeate or diffuse through the sealing material.
This undesired process also occurs at the lines, namely, at the lines for venting during operation and for venting during refueling as well as at the filler pipe. It is disadvantageous in this connection that a large outer surface area of the lines is present through which the gas can diffuse and reach ambient air from the interior of the fuel supply system.
In conventional systems, high-grade materials and complicated sealing systems are used for reducing the permeation of a fuel supply system.